1. Field Trial of a Pulsed Limestone Diversion Well U.S. Department of the Interior U.S. Geological Survey P. L. Sibrell USGS Leetown Science Center, Kearneysville, WV 25430 C. F. Denholm, M. H. Dunn Stream Restoration Inc., Mars, PA

2. Vertical Flow Pond AMD at Jennings Quonset Hut

3. 33 Diversion Well Schematic

4. Pulsed Limestone Bed System

5. Pulsed Diversion Well

6. Pulsed Diversion Well Advantages  Provides reproducible flow conditions at any flow rate up to design maximum.  Utilizes sand sized limestone for greater reactivity and increased rate of acid neutralization.  More attrition due to movement of intermittently fluidized limestone sand bed scours particles and reduces potential for armoring.  May be able to recycle CO 2.

7. Limestone Dissolution Rate Expression (Sverdrup, 1985) Reaction with hydrogen ion Reaction with carbon dioxide Reaction with H 2 O Backward reaction rate Mineral surface area

8. Siphon Doser Assembly

9. Siphon Sump

10. Limestone Sand Sump

11. Complete System

12. Limestone Size Distributions

13. Influent water quality parameters

14. Results – pH of Treated Water

15. Results – Alk of Treated Water

16. Laboratory Analysis

17. Winter Conditions

18. Plugging problems

19. CycloBio Reactor

20. Bottom Line  Modifications to the traditional diversion well, including use of a siphon doser and smaller limestone particle size, appear to offer advantages in acid neutralization and AMD treatment.  Air release from the delivery piping prior to the sand bed is an important consideration and must be allowed for.  Plugging of delivery lines and manifold orifices had a detrimental impact on performance.  Objectives for future testing include pipeline pigging and use of a CycloBio reactor to minimize plugging issues.